Question

Which of the following technique is used to separate chloroform and aniline?

• A. Fractional distillation
• B. Distillation under reduced pressure
• C. Steam distillation
• D. Continuous extraction
• E. Distillation

Hint:

Large boiling point difference $\Rightarrow$ simple distillation.

Answer 1

Answer: (E)

Step 1: Understanding Distillation Techniques:
Distillation is a process used to separate components of a liquid mixture based on differences in their boiling points. Different types of distillation are used depending on the properties of the components.
Simple Distillation: Used to separate a liquid from a non-volatile solute or to separate two liquids with a large difference in boiling points (typically>25 \(^{\circ}\)C).
Fractional Distillation: Used to separate two or more miscible liquids with close boiling points.
Steam Distillation: Used to separate substances that are steam volatile and immiscible with water.
Distillation under reduced pressure (Vacuum Distillation): Used to purify liquids that have very high boiling points or those that decompose at or below their normal boiling points.
Step 2: Analyzing the Properties of Chloroform and Aniline:
Chloroform (CHCl\(_3\)):
Boiling point: 61.2 \(^{\circ}\)C
A volatile organic liquid.
Aniline (C\(_6\)H\(_5\)NH\(_2\)):
Boiling point: 184.1 \(^{\circ}\)C
An organic liquid.
Chloroform and aniline are miscible liquids. The difference in their boiling points is \(184.1 - 61.2 = 122.9\) \(^{\circ}\)C.
Step 3: Choosing the Appropriate Technique:
Since there is a very large difference in the boiling points of chloroform and aniline (122.9 \(^{\circ}\)C, which is much greater than 25 \(^{\circ}\)C), they can be effectively separated by simple distillation. When the mixture is heated, the more volatile component (chloroform) will vaporize first, and its vapor can be collected and condensed back into a pure liquid, leaving the less volatile aniline behind. The option "Distillation" refers to this simple distillation process. Fractional distillation would also work but is more complex than necessary. Steam distillation is not suitable as chloroform is not typically purified this way in this context.
Step 4: Final Answer:
The large difference in boiling points allows for the separation of chloroform and aniline by simple distillation.